How do I delete data from a huge table?

Options to Delete the Data

1. Using TOP Clause. Another approach is to use a TOP clause with a DELETE statement to limit the number of rows deleted as shown below.
2. Using ROWCOUNT property.
3. Using a Cursor.
4. Using a While Loop.
5. Using GO with a count.
6. Generating the DELETE Statements.
7. Executing the File using SQLCMD.

How do I truncate a large table?

4 Answers

1. Truncate table.
2. Script out the table, then drop table and recreate the table using the script.
3. Assuming the table has a PK, then create a similar table, and using partition switch in/out to switch the table to the new table, and then drop the newly created table.

Which is faster TRUNCATE or DROP?

TRUNCATE is a DDL(Data Definition Language) command. It is used to delete all the tuples from the table. The TRUNCATE command is faster than both the DROP and the DELETE command. Like the DROP command we also can’t rollback the data after using the this command.

What’s the best way to delete a large table?

If you have a scheduled maintenance downtime window and you are able to take a consistent backup of the table immediately before the delete, you can use several methods: OPTION ONE: Use a vanilla delete with a COMMITs. Note that it is common for super-large tables to reside within their own tablespace for ease of management.

How to delete data from a large table in Oracle?

Vanilla delete: On a super-large table, a delete statement will required a dedicated rollback segment (UNDO log), and in some cases, the delete is so large that it must be written in PL/SQL with a COMMIT every million rows. Note that Oracle parallel DML allows you to parallelize large SQL deletes.

How to delete large data of table without log?

This will delete the data in selected partition (s) only and should be the most efficient way to delete data from part of table since it will not create transaction logs and will be done just as fast as regular truncate but without having all the data deleted from the table.

What happens when you delete a large amount of data?

But when you delete a considerable amount of data the row locking escalates into a page or even a table lock which causes blocking issues. When I was asked to remove historical data from a 120 GB unpartitioned table for an online payment service I tried different approaches, all with the same basic idea of limiting blocking issues.

How do I DELETE data from a huge table?

Options to Delete the Data

1. Using TOP Clause. Another approach is to use a TOP clause with a DELETE statement to limit the number of rows deleted as shown below.
2. Using ROWCOUNT property.
3. Using a Cursor.
4. Using a While Loop.
5. Using GO with a count.
6. Generating the DELETE Statements.
7. Executing the File using SQLCMD.

What would be the fastest way to DELETE all the rows from a table?

To delete every row in a table:

1. Use the DELETE statement without specifying a WHERE clause. With segmented table spaces, deleting all rows of a table is very fast.
2. Use the TRUNCATE statement. The TRUNCATE statement can provide the following advantages over a DELETE statement:
3. Use the DROP TABLE statement.

How to free space after deleting millions of rows from a table?

I performed a delete operation on my table . It deleted around 10 millions of rows from it How do I free the space associated with the deleted data. But it did not work for me. Do I need to concern about the index’s associated with the table?

Is there a way to reclaim space after a delete?

There is no way to reclaim space after delete. but if after the delete the size of the remaining data is relatively small then create a new table with the data, drop the old table and rename the new table to the old name.

Which is faster to delete rows or partitions?

Dropping a partition is essentially instantaneous, much faster than deleting that many rows. However, you must design the table so that the entire partition can be dropped. That is, you cannot have some items living longer than others. PARTITION tables have a lot of restrictions, some are rather weird.

How to free space associated with deleted data?

How do I free the space associated with the deleted data. But it did not work for me. Do I need to concern about the index’s associated with the table? If that is the case, how do I need to do it.